Helmet



FIG. 1 is a front, top and right side perspective view of a helmet showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a right side view thereof;

FIG. 4 is a left side view thereof;

FIG. 5 is an enlarged view showing the portion defined by crop lines 5-5 in FIG. 1; and,

FIG. 6 is an enlarged view showing the portion defined by crop lines 6-6 in FIG. 2.

The broken lines illustrate portions of the helmet and form no part of the claimed design. 

CLAIM The ornamental design for a helmet, as shown and described. 